Method of and means for attaching conductors



April 15 19242. 1,490,306

0. E. BECKER METHOD OF AND MEANS FOR ATTACHING CONDUCTORS Filed July 8. 1921 Patented Apr. 15, 1924.

UNITED STATES 1,490,306 PATENT OFFICE",

OLIVER E. BECKER, OF CHICAGO, ILLINOIS, ASSIGNO'R TO BECKER BROS, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

METHOD OF AND'MEANS FOR ATTAGHING CONDUCTdRS.

Application filed July 8, 19.21.

To all whom it may concern:

Be it known that I, OLIVER E. BECKER,

a citizen of the United States, residin at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Methods of and Means for Attaching Conductors, of

which the following is a full, clear, concise,

and exact: description,reference being had to W the accompanying drawings, forming a part of this specification.

My invention relates to electrical power equipment, and more specifically to the art of conveying electrical current. to or from an armatureor other moving member. The commutators or slipsrings carried by such members for direct or alternating current work respectively, usually make cont-act with stationary current carrying elements resiliently pressed. into sliding contact with the same. These stationary elements are usually of a composition comprising chiefly a carbon base, such. as graphite or coke, mixed with other ingredients to impart structural strength and: good wearing qualities to the composition, and are commonly known in the art. as brushes. While I have illustrated my invention in connection with a rigid granular brush, it will be. obvious that it is not liinitedto any particular type of brush.

As thebrush must be free to ride over thesurface of the rotating element in con- .tact therewith under the pressure of, resilient holding. means, flexible members called leaders or pig tails are usually employed to carry the current between the brush and the adjacent ends of the relatively rigid current-carrying cables used for conveying, electrical power.

In establishing a connect-ion between the pig tail and the brush, the mechanical requiremonts of strength and durability and the electrical requirements as to firm contact over a large area even, after prolonged service, are both rather exacting, and my invention is primarily concerned with improving the art OfiII12lkllflg this connection, so as to make it possible for thelayman to attach new carbons to pig tails thus avoiding the expense of supplying a new pig, tail when a carbon or graphite or similar brush has been consumed. or becomes unserviceable and elimiiii) Serial No. 483,207.

nate defects in service now commonly encountered, both as to electrical contact, which has to do with the electrical performanoe of the equipment, and as to mechanical strength and durability which has to do with breakage and the necessity for frequent repairs.

The object of my invention, therefore, is generally to improve the connection in question, providing for better transfer of the electrical current from one element to the other by means of a relatively simple and durable structural embodiment comprising a minimumlnumber of parts.

Other more detailed objects and ad vantages of my invention will become apparent as the description proceeds.

In the accompanying drawings: 7

Figure l is an isometric view of one embodiment of my invention.

Figures 2 and 3 are partly diagrammatic views illustrating two successive steps in the process of forming my improved connection, and

Figure is a view generally similar to Figure 3 showing a. modified form of connection.

Figures 5 and 6 are fragmentary transverse sections, on a much enlarged scale, illustrating the condition of the ends of the pig tail before and after the forming operation.

Figure 7 is an elevation of the end of a. finished pig tail, and

Figure 8 is a. similar elevation showing the product obtained in a modified process involving the addition of one step to the process of manufacturing the pig tail, and the elimination of a step from the process of assembling the .pig tail and the brush.

Fignref) is an elevation of a sleeve with a slotted end. and

Figure 10 shows analternative method of forming the threads.

Attempts have been made in. the prior.

art to form a connection by soldering a threadeijl sleeve 01 ferrule onthe end of the pig tail. and screwing the ferrule into the body of the brush, with the screw threads of various shapes. factory service rendered by such connections, I believe to beattributable to the fact that neither the connection betweenthe pig tail and the ferrule, nor the connection be- The generally unsatis tween the ferrule and the brush, are adapted to secure a satisfactory union between the parts either mechanically or electrically. It the sleeve were always completely filled with a mass of solder, terminating substantially flush with both ends of the sleeve. the connection between the pig tail and the sleeve might be fairly satisfactory, but such precision in applying solder is believed to be considerably beyond the skill of an. ordinary worlnnan, or the best performance of machines for doing this work. It the sleeve is only part full of solder, the contact area between the sleeve and the pig taii may be very considerably reduced, and. the loose end oi the pig tail where it leaves the sleeve will he moved back and forth against the edges or" the sleeve. tearing the individual strands. It the solder fills the sleeve and also tlows over beyond. the end of the sleeve, the projecting lump of solder increases the rigid end portion of the connection beyond that intended, and where the individual fibres of the pig tail leave the mass oi solder, they will be subjected to very sharp bending. Such a pig tail will break off even more easily than one in which the sleeve is not completely filled with solder.

A soldered sleeve, moreover. is apt to make trouble in occasional periods of severe service, often of such short duration that the rest of the equipment would not fail in any way, by melting out the solder. The heat of the solder when it is put in place, will more or less oxidize the surfaces it congeals in contact with. resulting in increased rcsistance which always represents a loss of pOWer, and generating heat to help melt the solder under a momentary overload. The size of sleeve required is also greater for a given size of pig tail than I need to employ as the sleeve must fit loosely over the pig tail before soldering, and retain its original dimension in the finished product.

Corrosion not used. mechanical much less.

According to my invention. the end of the pig tail la is inserted in sleeve 16, and union between the sleeve and pig tail is produced by deforming the sleeve. crushing it inwardly to a smaller diameter between dies 18 and 20 to compact the .tibres of the pig tail and firmly grip them in the sleeve. Figures 5 and 6 illustrate on an enlarged scale the condition of the sleeve and fibres before and after compression in the dies. It will be seen that the originally loose individual fibres 22 have been jammed against each other. and more or less actually imbedded in the material 0]": the sleeve 16.

The dies 18 and 20 are preferably deis eliminated when solder is Also the cost of making such a connection without solder 18 signed to form the end of sleeve 16 into a noncircular shape, so that a finished article may be engaged by a wrench or other suit-- able tool ior rotating the same. In Figure 3, the sleeve after the dies operate on it, is shown as having an oblong end, although the end may obviously be formed square instead as indicated in Figure 4:.

The pig tail and sleeve are now removed trom the dies, and screw threads 18, are termed on the cylindrical portion of the sleeve. I prefer to torm these threads by rolling, partly l)t""{lllS8 such a method is cheaper, but especially been use such a method ot forming the threads will tend to increase rather than decrease the gri niin; action between the sleeve and the fibres oi the pig tail.

The threads formed should preferably be sharp 60 threads to secure a large contact area with the material. of the brush.

In the modification of my invention employing the type of sleeve illustrated in. Figure 8. I avoid tapping the hole in the brush 12 with a separate tap, by cutting flutes 21 in substantially one-third or one-half of the length of the threaded portion of the sleeve. Although the sleeve is formed of relatively soft metal, this metal is harder than the material of which brush 12 is composed, and such a sleeve as shown in Figure 8 may be screwed into a drilled hole in the brush, without tapping the hole. The material removed from the body of the brush by the tap-like portion at the end of the sleeve will jam and choke in the threads oi the portion beyond the flutes 24 to assist in forming a firm union between. the sleeve and the brush.

Instead of flutes 24 which make a tap out of the sleeve, I may cut slots 26 to define resilient end portions. In using a pig tail successively with a plurality of brushes, the resilient fingers thus formed will press firmly against the thread in the brush, regardless of whether there is a perfect fit along the non-resilient portions or not. In certain classes of work, when slots 26 are cut in the sleeve, the screw threads may be omitted, and contact of the resilient fingers with the sides of the hole may be relied on for electrical union of the parts. and for frictionally holding the parts in mechanically nssem bled position.

The non-circular portion 16 is useful, not only in inserting the sleeve in the brush, but also during the process of threading the sleeve, whether this is performed by rolling or by cutting with the customary die. In Figure 10 the sleeve is illustrated as clamped in the jaws 28 of a chuck, or an automatic screw machine, while the threads are being machined by die 30. If desired, the end of the sleeve may be rounded in or tapered as at 32, to facilitate its insertion into the brush, and also to bind in the fibers of the leader to prevent any loose strands from projecting and from catching in the die.

Without further elaboration, the foreg0- ing will so fully explain the gist of my invention, that others may, by applying current knowledge, readily adapt the same for use under various conditions of service without eliminating certain features which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by I the following claims.

I claim:

1. The method of assembling a pig tail with a threaded ferrule on its end which comprises inserting the end of the pig tail in the ferrule, deforming the ferrule to grip the pig tail and subsequently forming threads in the outer surface of the ferrule.

2. In. combination, a brush body, a con ductor, a connecting sleeve between the conductor and brush body, said sleeve receiving and being shrunk on the conductor, and having a non-circular end, a central threaded portion and a terminal portion formed in the shape of a tap for threading the sleeve into the brush body.

3. In combination, a fibrous metal pig tail and a metal ferrule mechanically compressed or shrunk upon the end of the pig tail, said ferrule having its end slotted to form resilient fingers.

4. In combination a stranded conductor and a cylindrical sleeve permanently shrunk upon one end of the conductor said sleeve having its outer end threaded and its inner end deformed to adapt it to be engaged by a suitable wrench.

5. The method of fastening a pig tail into a brush which comprises shrinking a sleeve permanently upon the end of the pig tail, forming threads upon said sleeve after it is on the pig tail, and threading the outer end of said sleeve into a hole in the brush.

6. In combination a stranded pig tail conductor, a cylindrical metal sleeve permanently shrunk upon the end of the pig tail, said sleeve having threads, and having a longitudinal groove across the threads to form a tap like extremity on said sleeve to aid it in cutting its way into the material of a brush.

7 In combination a brush having a hole .formed in but not through the same and a pig tail having a metallic sleeve fastened upon the outer end thereof, said sleeve being inserted into the hole toward the bottom thereof and having means for firmly engaging the sides of the hole within the body of the brush to hold the pig tail and brush in permanent electrical union.

8. In combination a brush having a hole therein, a pig tail having a threaded sleeve upon the end thereof, the front end of the sleeve terminating substantially coincident with the end of the pig t'ail, the front end of the sleeve being threaded into the hole in the brush.

9. In combination a brush having a hole therein lying parallel to the longitudinal axis of the brush, a stranded pig tail conductor, a cylindrical metal sleeve permanently shrunk upon the end of the pig tail said sleeve having threads thereupon and said sleeve being threaded into the hole in the brush so that the pig tail extends endwise out of the rear end of the brush.

In witness whereof, I hereunto subscribe my name this 5th day of July, 1921. 7

OLIVER E. BECKER. 

